<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script>
			var a = 1;
			var b = true;
			var c = a+b;
			document.write(c+'<br/>');
			
			
			var a1 = '1';
			var b1 = true;
			var c1 = a1+b1;
			document.write(c1+'<br/>');
			
			
			var a2 = new Object(1);
			var b2 = true;
			var c2 = a2+b2;
			document.write(c2+'<br/>');
			
			
			var a3 = null;//0 flase
			var b3 = true;//1
			var c3 = a3+b3;
			document.write(c3+'<br/>');
		</script>
	</head>
	<body>
	</body>
</html>
